CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Mandatory Convertible Preferred Shares Preferred Stock	Common Shares	Capital in Excess of Par Value	Accumulated Other Comprehensive Income	Retained Earnings	Treasury Shares	Non-controlling Interest	Total
Balance at the beginning of the period at Dec. 31, 2017		$ 368	$ 2,791,129	$ 11,185	$ 1,423,154	$ (1,314,020)	$ 26,957	$ 2,938,773
Balance (in shares) at Dec. 31, 2017		367,510,000
Increase (Decrease) in Equity
Net income (loss)					(144,201)		539	(143,662)
Dividends to common shareholders					(19,050)			(19,050)
Other comprehensive income (loss), net of tax				(18,336)			(96)	(18,432)
Issuance of common shares for stock options exercised, net of surrender of unexercised stock options			8,628					8,628
Adjustment to retained earnings | Accounting Standards Update 2016-01					9,144			9,144
Adjustment to retained earnings | Accounting Standards Update 2016-16					(34,132)			(34,132)
Adjustment to retained earnings				(9,144)
Less: accrued distribution on redeemable noncontrolling interest in subsidiary					(2,399)			(2,399)
Other		$ 2	(1,864)					(1,862)
Other (in shares)		2,810,000
Balance at the end of the period at Mar. 31, 2018		$ 370	2,797,893	(7,151)	1,232,516	(1,314,020)	27,400	2,737,008
Balance (in shares) at Mar. 31, 2018		370,320,000
Balance at the beginning of the period at Dec. 31, 2018	$ 6	$ 410	3,392,937	(29,325)	650,842	(1,314,020)	49,476	2,750,326
Balance (in shares) at Dec. 31, 2018	5,750	409,652,000
Increase (Decrease) in Equity
Net income (loss)					(117,709)		14,176	(103,533)
Dividends to common shareholders					(3,947)			(3,947)
Dividends to preferred shareholders ($0.75 per share)					(4,313)			(4,313)
Other comprehensive income (loss), net of tax				9,338			52	9,390
Share-based compensation			8,424					8,424
Adjustment to retained earnings								0
Less: accrued distribution on redeemable noncontrolling interest in subsidiary					(5,063)			(5,063)
Other		$ 6	(1,251)					(1,245)
Other (in shares)		6,264,000
Balance at the end of the period at Mar. 31, 2019	$ 6	$ 416	$ 3,400,110	$ (19,987)	$ 519,810	$ (1,314,020)	$ 63,704	$ 2,650,039
Balance (in shares) at Mar. 31, 2019	5,750	415,916,000